A treatise on prayer by a great early Christian theologian from Alexandria. Using prayers from both the Old and New Testament as examples, he creates a primer on what sort of things a Christian should pray for, and how. His primary tool for doing this is a detailed interpretation of the Lord's Prayer.
Some of the theology, Biblical interpretation, and Christian practice that he advocates has been developed further since his time. So you may need to take these bits with a grain of salt. But much of his advice and insight is still good today, as well as serving as an interesting slice of historical life.
Complete in 20 chapters.
Stop by http://marialectrix.wordpress.com for more audiobook podcasts.